The subject matter disclosed herein relates to a late lean injection (LLI) manifold.
In gas turbine engines, mixtures of fuel and gas are combusted within a combustor disposed upstream from a transition piece and a turbine to produce high energy fluids from which mechanical energy can be derived for the generation of power and electricity. The high energy fluids are continually reused until significant levels of power generation cannot be derived at which point they are exhausted into the atmosphere. This exhaust often includes pollutants produced during the combustion, such as nitrous oxides (NOx) and carbon monoxide (CO).
Efforts have been expended to reduce the amount of pollutants produced by the combustion processes and include the development of late lean injection (LLI). LLI involves the injection of combustible materials into the flow of the high energy fluids at a location downstream from the normal combustion zone in the combustor. This downstream location could be defined as a section of the combustor liner or at a section of the transition piece. In any case, the combustible materials injected at this location increase temperature and energy of the high energy fluids and lead to increased consumption of CO and little to no significant increase in NOx for reasonable levels of LLI fuel flow.
In order to build LLI combustors or to refit currently operating combustors for LLI operations it has been necessary to employ relatively complex fuel and/or gas lines and to form holes in combustor liners and/or transition pieces by which LLI fuel can be injected. There are, however, significant mechanical challenges in routing fuel into the hot compressor discharge plenum and delivering it to the combustor in an effective, robust and durable way.